Aspirin

Aspirin, or acetylsalicylic acid, is a widely used nonsteroidal anti-inflammatory drug (NSAID). It provides analgesic, antipyretic, and anti-inflammatory effects and, at low doses, acts as an antiplatelet agent by irreversibly inhibiting platelet COX-1.

Aspirin works by acetylating cyclooxygenase enzymes, reducing prostaglandin and thromboxane synthesis. The antiplatelet effect arises from irreversible COX-1 inhibition in platelets, lowering thromboxane A2 and diminishing clot formation. The antiplatelet action lasts for the platelet lifespan, about 7 to 10 days.

Common uses include relief of mild-to-moderate pain, reduction of fever, and management of inflammation. In cardiovascular medicine, low-dose aspirin is used for secondary prevention to reduce the risk of heart attack or stroke; its role in primary prevention is individualized due to bleeding risk.

Aspirin is usually taken orally in tablet form, with analgesic dosing typically 325–1000 mg every 4–6 hours, and antiplatelet dosing of 75–100 mg daily. Formulations include regular and enteric-coated tablets; usage in children is limited due to Reye’s syndrome risk.

Safety and side effects include gastrointestinal irritation, ulcers, and bleeding; at higher doses, tinnitus and hearing loss may occur. A rare but serious risk is Reye’s syndrome in children and teens with viral infections. Aspirin can interact with anticoagulants, other NSAIDs, alcohol, and certain medications.

Aspirin was developed by Bayer in the 1890s and marketed in 1899; the name reflects the acetylation of salicylic acid derived from willow bark.